Impervious paper board and process for making the same



G. H. ELLIS June 18, 1929.

IMPERVIOUS PAPER BOARD AND PROCESS FOR MAKING THE SAME Filed March 26,192 5 Patented June 18, 1929.

UNITED STATES PATENT OFFICE. I

GEORGE E. ELLIS, 01 S1. PAUL, MINNESOTA. I IMPER'VIOUS PAPER BOARD ANDPROCESS FOR MAKING THE SAME.

Application filed m 26,1923. Serial No. 627,689.

The object of my invention is to provide a paper board which isiIIlPGlVlOUS'tO mo sture and air, and free from characteristics whichwill injure foodor other products in contact therewith. A further objectis to produce such a board of durable character cheaply andeconomically.

It is also my object to provide such a board with surfaces which areadapted to receive printing or other desirable trade dress thereon.

The increased demand for'paper bo rd cartons and packing cases as asubstitute or wooden boxes has resulted in attempts to produce a paperboard impervious to air and moisture as well as free from odordetrimental to the contents, and without oiled or glazed surfaces, whichmake printing upon the exterior of the carton difficult or unsightly.

It is a matter of common knowledge that parafline has been used to waterproof such cartons and that cartons have also been produced by pastingor cementing ordinary paper over water proof fiber sheets. The lattermethod is laborious and expensive, while the parafline is apt to rub orchip off the outer surface and make printing or other trade dressthereon unsightly.

My present invention makes the use of parafiine unnecessary, and, ascompared with the built up paper board above mentioned,

eliminates much labor and expense, and results in a tough, lightimpervious paper board which is both durable and sightly, as well asadapted to receive printing or other marks or illustrations.

Referring to the accompanying drawings,

. which illustrate diagrammatically a paper '1' is a side elevation ofone end thenumerals 1 to 5 inclusive,

machine suitable for carrying out the process of the present inventionin the manufacture of my improved, impervious board, Figure of themachine and Figure 2 is a transverse section through one of the cylindermoulds and the adjacent vat. i

The machine is of a well known type, having a series of cylinder mouldsindicated by said cylinders being severally mounted in vats 6 to 10.Paper stock which has been prepared in the heaters, is pumped intothrough pipes 11 and partially submerges the cylinder moulds. naled onsuitable shafts in the ends of the vats and consist of a grid frame work12 and-coarse mesh backing wire the several vats not impossible, tomake, The moulds are jour- Wheels 13, 14 and an outer fine mesh wire 15through which the excess water from the paper stock passes into theinterior'of each cylinder 'Water passes out from within the cylindersthrough suitable weirs (not shown) in the ends of the cylinders.

As liquid from the vat flows inwardly through the wire covering of eachcylinder mould, the fibrous pulp is deposited on the exterior of thewire 15 and forms the paper Web. An endless felt belt 16 is pressed uponthe upper periphery of the cylinder moulds by a series of couch rolls 17said belt being (Fig. 2) supported on suitable driven by suitable means(not shown). The

a pair of making rolls 19', where its upper surface is brought incontact with the lower surface of an upper felt belt 20. The felts 16and 20 carry the paper web between their ad acent surfaces to a pair ofsuction rolls 21 where a large amount of the moisture is withdrawn fromthe web. 'From the suction rolls 21 the web is carried between squeezingrolls and then through a series of press rolls to the drying cylindersin the usual manner.

My -improved board, made in a machine of the above described class, iscomposed of a plurality of layers of paper stock with an interposedlayer of impervious, adhesive stock. F or the impervious and adhesivestratum of the board, I prefer to use stock made in accordance with thespecification of my Patent N 0. 1,449,221, dated March 20th, 1923,insulating boards andprocess of making the same. The bitumen used in theimpervious layer of my improved board is liquid at normal temperaturesanddoes not harden or become brittle in the finished product.- I havefound in practise that such stock may heres thereto and produces astrong and durable board, which is most desirable for making cartons andpacking cases.

Obviously, it would be impracticable, if

in a cylinder machine,"paper board composed entirely of the sticky,impervious stock made by my above described patented process because thebitube used as hereinafter described I without gummin'g the mechanism ofa paper 7 men in the web would gum up the felt and rolls of the machine.

layers by 40 However, in the present process, I incorporate theimpervious layers between layers of nonadhesive aper stock in such amanner that only the atter layers come in contact with the felt, androlls of the machine.

To this end, as the felt 16 passes successively over the upperperipheryof the cylinder moulds 1, 2, 3, 4, and 5, a layer of ordinary paper pulpis supplied to the end cylinders while the above described imperviouspulp is supplied to one or more of the intermediate cylinders so thatthe nonadhesive layers protect the felt and rolls of the machine fromthe bituminous ma-v terial.

To secure this result, the pulp supplied to the vats 6, 7 and 10 is ofthe common paper stock, which is pervious and nonadhesive, while thestock supplied to the vats 8 and 9, is preferably prepared as describedin my above mentioned prior patent, that is, the pulp.in the vats 8 and9 is impregnated or coated with bitumen so that the paper web formedtherefrom is adhesive and impervious to moisture and air. Thus, as thefelt 16 passes over the cylinder moulds 1 and 2, layers of pervious,nonadhesive stock are applied to the felt. The web thus formed isnowcarried by the felt over the moulds 3 and 4', where the impervious,sticky layers are placed upon the nonadhesive layers. Finally, anotherlayer of pervious material is applied by the mould 5 to the adhesivematerial so that the felt 20, which is later pressed upon the uppersurface of the web, is separated from the adhesive a layer ofnonadhesive paper stock; A box board is thus formed in a singleoperation which, when passed through the usual hot or finishing rolls,is highly impervious to moisture and air and is, during the process,prevented from adhering to the parts of the cylinder machine.

Obviously, the number and thickness of the pervious and imperviouslayers incorporated inthe board, maybe varied as desired,withoutdeparting fromthe spirit of my invention.

Having described my invention and what I claim as new and desire toprotect by positing an impervious adhesive web con-.

taining liquid bitumen on said first mentioned web in said machine andsubsequently applying a web of pervious stock to the exposed surface ofsaid adhesive web and finally compressing and drying said webs to form amultiple ply board suitable for making boxes. 7

2. The process formaking an impervious paper board, which consists infirst applying a web of nonadhesive stock to the felt of a cylinderpaper machine, then depositing a web of adhesiveimaterial' containing.liquid bitumen upon said first mentioned web and finally applying a webofmonadhesive stock to the exposed surface of said web containingbitumen 3. The process of making an impervious paper board whichconsists in forming a web of nonadhesive stock, then pressing a web ofimpervious, adhesive stock impregnated with liquid bitumen on said firstmentioned web; then molding a web of nonadhesive stock on the exposedsurface of said impervious web and finally compressing and v drying saidwebs into a multiple ply board suitable for making boxes. .4. A. boxboard comprising a plurality of layers of absorbent stock and anintermediate self cohering layer of saturated paper stock forming anintegral sheet having ervious surfaces with a core waterproo ed withbitumen which remains fluid at normal temperatures. f

In tatimony whereof, I have hereunto signed my name to this secificati'on.

' GEOR E H.'ELLIS.

for making an impervious

